Biology Paper 1 Exam Questions I will Get Right

• A student investigated photosynthesis using pondweed.

  Switch on the lamp.

  After 20 minutes, record the volume of oxygen collected in the measuring cylinder.

  Repeat using bulbs of different power output.

  Suggest two ways the method could be improved so the results would be more valid. [2 marks]

  control the distance of the bulb from the pondweed

  control the mass / length / species / age of the pondweed
• Explain how diabetes can cause the body cells to lose more water. [3 Marks]

  the blood is more concentrated

  water moves out of cells by osmosis

  water moves through a partially permeable membrane
• Describe how the small intestine is adapted for efficient absorption.


  villi provide a large surface area

  capillaries one cell thick for shorter diffusion distance

  (small intestine is) very long, increasing time (for absorption)~ efficient blood supply to maintain concentration gradient

  cells have many mitochondria which release energy for active transport
• Define the term double circulatory system


  blood is pumped to the lungs by right side of the heart and blood is pumped to the body by the left side of the heart.
• Explain why having only one ventricle makes the circulatory system less efficient than having two ventricles. [ 2 Marks]

  oxygenated and deoxygenated blood mixes

  less oxygen reaches the body
• Explain why an axolotl may die in water with a low concentration of oxygen

  concentration gradient (of oxygen) is shallower

  less oxygen diffuses into blood

  anaerobic respiration occurs so less energy is released

  lactic acid is produced- toxic
• Name the type of cell that divides when a new gill grows.

  Strem Cells
• Suggest one reason why an axolotl is a suitable animal for research in the laboratory.

  • easy to breed
• An axolotl may not be a suitable animal to study when researching regeneration in human tissue. Suggest one reason why.

  regeneration in gills may be different to that in other organs or

  metabolism / body processes are too different to humans
• What is an enzyme? [2 Marks]


  Biological catalyst which speeds up ROR

  Is a Protein
• Carbohydrase is an enzyme produced by the pancreas


  salivary gland

  small intestine
• Explain how pancreatic cancer may cause a person to lose weight


  reduced enzyme production

  food is not broken down fully

  less glucose absorbed

  fewer amino acids absorbed

  fewer amino acids are available for making new proteins
• reasons why a placebo and a double-blind trial were used.

  to avoid bias

  to take into account a psychological effect
• Explain how the monoclonal antibody works to treat pancreatic cancer.


  monoclonal antibody is attached to toxin

  monoclonal antibody will (only) attach to target cells

  chemical will (bind to cancer cells and) stop them growing
• Suggest one possible cause of the anomalous result. Rate of Photsynthesis is too high


  the lamp / light was moved

  temperature changed
• Why did the rate of photosynthesis decrease from 35 °C to 45 °C?

  enzyme(s) lose the shape of the active site
• Which two changes will increase the rate at which carbon dioxide diffuses into the mesophyll cells?

  increased carbon dioxide concentration in the air

  increased number of stomata that are open
• Explain how the human lungs are adapted for efficient exchange of gases by diffusion. [6 marks]

  alveoli provide a large surface area

  capillaries are one cell thick, short diffusion distance

  lungs are ventilated : to bring in (fresh) oxygen

  to remove carbon dioxide

  to maintain a concentration / diffusion gradient

  good blood supply

  to remove oxygen(ated blood) quickly

  to bring carbon dioxide to the lungs quickly
• two similarities between the prokaryotic cell and the eukaryotic cells


  (cell) membrane

  DNA
• Describe what happens during each stage of the cell cycle

  DNA Replication

  subcellular structures replicate

  one set of chromosomes pulled to either end of cell

  cell memerbane and cytoplasm DIVIDE.
• Explain the ‘lock and key theory’ of enzyme action [3 marks]

  enzyme binds to the substrate because they are complementary shapes

  substrate is broken down

  products are released
• test for starch. [2 marks]


  add iodine SOLUTION

  it changes colour to blue / black
• Explain why the leaf in the light for four days contained both glucose and starch. [2 marks]


  glucose from photosynthesis

  glucose converted to starch
• Explain why the leaf left in a cupboard with no light for two days did contain glucose but did not contain starch. [3 marks]

  starch has been converted to glucose

  used for respiration

  used to release energy as there is no light to make

  glucose by photosynthesis
• Suggest one way the students could develop the investigation to find out more about glucose and starch production in plants [1 mark]


  test other species of plant

  vary time in light/dark
• How do thorns defend the gorse plant?


  deter animals from eating it
• Explain two other possible reasons for the yellow leaves and stunted growth.

  lack of magnesium not enough chlorophyll for photosynthesis

  lack of light chlorophyll breaks down
• Decribe the heart and its functions 


  right ventricle pumps blood to the lungs where gas exchange takes place.

  The left ventricle pumps blood around the rest of the body.

  blood vessels associated with the heart:

  aorta

  vena cava,

  pulmonary artery,

  pulmonary vein

  coronary arteries.
• Suggest how the nodules benefit the bacteria

  obtain glucose for respiration
• Explain how the nodules benefit the gorse plant. [2 marks]


  obtains nitrate (ions) needed for amino acids / proteins
• Which plant material was chewed as a painkiller?

  willow bark
• Suggest two other factors which the scientists would have controlled


  BMI

  smoking habits

  diet

  medication
• Suggest two reasons why the data is considered to be valid

  • large number in survey

  • well controlled
• Suggest one aspect of the survey which might reduce validity

  Peopel may lie
• Describe the effects of liver failure on the human body. [4 marks]

  proteins / amino acids will not be broken down

  will not form ammonia but

  any ammonia formed is toxic

  liver does not break down toxins

  or remove other toxins

  toxins accumulate in blood body will be poisoned
• a fluorescent dye could be used to see any Candida albicans pathogens on the slide

  bind fluorescent dye to mAbs put

  fluorescent mAbs on the slide

  mAbs pathogens and show up under the microscope
• Explain how increased phagocytosis of the Candida albicans pathogen will help the patient

  pathogens will be engulfed

  therefore less damage to cells / tissues / organs
• Suggest one reason why these new mAbs have been more successful in treating diseases in humans than mAbs made using mice.

  the human lymphocytes have already responded to that infection
• Explain why the red blood cell bursts but the plant cell does not burst. [2 marks]

  water enters by osmosis

  plant cell has a cell wall
• Suggest one way the student could improve the investigation. [1 mark


  Repeat and Calculate a mean